// 导出页面为PDF格式
import html2canvas from "html2canvas"
import JSPDF from "jspdf"
export default {
    install (Vue, options) {
        Vue.prototype.ExportSavePdf = function (htmlTitle, currentTime) {
            var element = document.getElementById(htmlTitle)
            html2canvas(element, {
                logging: false
            }).then(function (canvas) {
                var pdf = new JSPDF("p", "mm", "a4") // A4纸，纵向
                var ctx = canvas.getContext("2d")
                var a4w = 170; var a4h = 257 // A4大小，210mm x 297mm，四边各保留20mm的边距，显示区域170x257
                var imgHeight = Math.floor(a4h * canvas.width / a4w) // 按A4显示比例换算一页图像的像素高度
                var renderedHeight = 0

                while (renderedHeight < canvas.height) {
                    var page = document.createElement("canvas")
                    page.width = canvas.width
                    page.height = Math.min(imgHeight, canvas.height - renderedHeight)// 可能内容不足一页

                    // 用getImageData剪裁指定区域，并画到前面创建的canvas对象中
                    page.getContext("2d").putImageData(ctx.getImageData(0, renderedHeight, canvas.width, Math.min(imgHeight, canvas.height - renderedHeight)), 0, 0)
                    pdf.addImage(page.toDataURL("image/jpeg", 1.0), "JPEG", 10, 10, a4w, Math.min(a4h, a4w * page.height / page.width)) // 添加图像到页面，保留10mm边距

                    renderedHeight += imgHeight
                    if (renderedHeight < canvas.height) { pdf.addPage() }// 如果后面还有内容，添加一个空页
                    // delete page;
                }
                pdf.save(currentTime)
            })
        }
    }

}
